1. Field of the Invention
The present invention relates to a process for the preparation of a film-forming liquid resin dispersion from a thermoplastic polyester.
More particularly, the present invention relates to a process for the preparation of liquid resin dispersions characterized by dispersing a surface active polyester in a collodial form in water or an aqueous solution containing a small amount of a base and grafting a vinyl compound monomer and/or an acrylic or methacrylic acid ester monomer to the surface active polyester.
2. Description of Prior Arts
It is well known in the art that aqueous resin dispersions called "latexes" or "emulsion", which are obtained by emulsions polymerization of monomers such as ethylene, butadiene, styrene, vinyl acetate and acrylic acid esters are valuable as adhesives, coating agents and binders. As another process for the preparation of liquid resin dispersions, there can be mentioned a process comprising bulk- or solution-polymerizing a monomer and dispersing the resulting polymer, directly or after removal of the polymerization solvent, in water by using a water-soluble protective colloid or an emulsifier, if necessary with the aid of a small amount of an organic solvent, by means of a colloid mill or a homogenizer. According to this process, in order to obtain a colloidal dispersion, a large amount of a protective colloid an emulsifier must be used. Such additive tends to have bad influences on the film-forming polymeric material. For example, the additive is poor in the compatibility with the dispersed polymer or inhibits normal formation of a film. Further, the additive degrades the mechanical strength of the film or drastically lowers the water resistance of the film. Moreover, the additive weakens the adhesion between the resin film and the surface of a coated article.